Currently, displays are widely used in various smart devices, such as smartphones, MP3s/MP4s, wearable smart watches, smart bands and panel computers etc. With the spread of various smart devices, people have developed more and more requirements in screen brightness of the display. In the related art, an optical sensor is used for monitoring ambient luminance so as to adjust the screen brightness intelligently. However, the adjusted screen brightness cannot meet the individual requirements of every user, so the user may have to adjust the screen brightness manually each time, thus the operation is complicated and the experience of using the smart device is directly affected.